1. Field of the Invention
The present invention generally relates to systems and apparatus for determining the state of multiple sensors within magnetic proximity to one another and are implanted within a living being, and more particularly, to sensors including switches that tune and detune a plurality of sensors selectively.
2. Background
The assignee of the present invention has developed and commercialized wireless pressure sensors utilizing an LC circuit encased in a hermetic housing. The resulting sensor exhibits a characteristic resonant frequency. An external interrogation unit monitors a single sensor at a time by monitoring the electrical characteristics of the LC circuit. Multiple sensors in a single host can be interrogated on the condition that they are sufficiently far away from one another, in relative distance or in relative resonant frequencies, such that the external electronics can detect and independently acquire the signal from the sensor of interest without any parasitic effects caused by other sensors. Yet, if the sensors are too close to each other, the signal is compromised and an accurate reading can be difficult to obtain.
It is desirable to be able to detect physical characteristics, e.g., pressure or temperature, via passive, wireless sensors at locations in close proximity. Thus, there is a need for a reliable and reversible way to selectively turn on and off wireless sensors while retaining the benefits of passivity.